Aqueous polymer dispersions, a method for their preparation and the use thereof as pour-point depressants for crude oil, petroleum, and petroleum products

Abstract

The invention relates to aqueous polymer dispersions comprising at least one polymer obtainable by the reaction of at least one monomer M1 of the general formula H.sub.2CCHC(O)OR (I), wherein R is an unbranched alkyl chain comprising from 18 to 22 carbon atoms, and optionally at least one monomer M2. The invention relates moreover to a method for the preparing of such aqueous polymer dispersion and the use thereof as pour point depressant for crude oil, petroleum, and petroleum products.

Claims

1. An aqueous polymer dispersion comprising water and further comprising a) 10 to 55% by weight based on the dispersion of at least one polymer P obtainable by the reaction of reactive monomers M, wherein the reactive monomers M comprise 50 to 100% by weight of at least one monomer M1 of the general formula (I)
H.sub.2CCHC(O)OR(I) wherein R is an unbranched alkyl chain comprising from 18 to 22 carbon atoms; and 0 to 50% by weight of at least one monomer M2, which is different from monomer M1; wherein the amounts of the monomers M1 and M2 are each based on the total amount of all reactive monomers M used in the reaction, wherein the polymer P has a weight-average molecular weight M.sub.w of 20,000 to 150,000 g/mol according to DIN 55672-1:1995-02; and wherein the polymer P is present in the form of particles having an average particle size d.sub.50 of from 75 nm to 400 nm effected by Column Hydrodynamic Chromatography; b) 0 to 24.5% by weight based on the total amount of the aqueous polymer dispersion of at least one miscible solvent, c) 5 to 30% by weight based on the total amount of the aqueous polymer dispersion of at least one hydrophobic organic solvent, d) 10 to 30% by weight based on the total amount of monomers M of at least one protective colloid, wherein the at least one protective colloid is a polymer obtained by the reaction of 15 to 40% by weight of acrylic acid, methacrylic acid, or a mixture thereof; and 60 to 85% by weight of methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, styrene, alpha-methyl styrene, or a mixture of two or more thereof, wherein the given amounts are each based on the total amount of the at least one protective colloid; and e) 0 to 5% by weight based on the total amount of the aqueous polymer dispersion of at least one surfactant.

2. The dispersion according to claim 1, wherein the at least one monomer M1 is a mixture, comprising 40 to 55% by weight, based on the total amount of monomers M1, of monomers M1 of formula (I), wherein R is an unbranched alkyl chain comprising 18 carbon atoms; 10 to 15% by weight, based on the total amount of monomers M1, of monomers M1 of formula (I), wherein R is an unbranched alkyl chain comprising 20 carbon atoms; and 35 to 45% by weight, based on the total amount of monomers M1, of monomers M1 of formula (I), wherein R is an unbranched alkyl chain comprising 22 carbon atoms.

3. The dispersion according to claim 1, wherein the amount of the at least one monomer M2 is from 4 to 10% by weight based on the total amount of all reactive monomers M.

4. The dispersion according to claim 1, wherein the at least one monomer M2 is selected from the group consisting of acrylate monomers of the general formula (II),
H.sub.2CCHC(O)OR.sup.3(II), wherein R.sup.3 is a branched or unbranched alkyl chain comprising from 1 to 10 carbon atoms; methacrylate monomers of the general formula (III)
H.sub.2CC(CH.sub.3)C(O)OR.sup.4(III), wherein R.sup.4 is a branched or unbranched alkyl chain comprising from 1 to 10 carbon atoms; and styrene monomers.

5. The dispersion according to claim 1, wherein the at least one monomer M2 is butyl acrylate or 2-ethyl hexylacrylate.

6. The dispersion according to claim 1, wherein the at least one miscible solvent is 1,2-propylene glycol.

7. The dispersion according to claim 1, wherein the at least one protective colloid is a polymer obtained by the reaction of 15 to 30% by weight of acrylic acid, methacrylic acid, or a mixture thereof; and 70 to 85% by weight of methyl methacrylate, n-butyl acrylate, 2-ethylhexyl acrylate, styrene, alpha-methyl styrene, or mixtures thereof, wherein the given amounts are each based on the total amount of the at least one protective colloid.

8. The dispersion according to claim 1, wherein the at least one hydrophobic organic solvent is an aromatic or aliphatic hydrocarbon or a mixture thereof.

9. The dispersion according to claim 1, wherein the at least one surfactant is a nonionic surfactant of the general formula (IV)
R.sup.5O(CH.sub.2CH.sub.2O)H(IV) wherein R.sup.5 is a branched or unbranched alkyl radical having 12 to 22 carbon atoms; and n is 5 to 30.

10. The dispersion according to claim 1, wherein the polymer P has a weight-average molecular weight M.sub.w of 20 000 to 100 000 g/mol.

11. A method for the preparation of the aqueous polymer dispersion according to claim 1, comprising the steps of a) preparation of an aqueous monomer dispersion comprising water and further comprising a1) 10 to 55% by weight based on the total amount of the resulting aqueous polymer dispersion of reactive monomers M, wherein the reactive monomers M comprise 50 to 100% by weight based on the total amount of the reactive monomers M of at least one monomer M1 of the general formula (I)
H.sub.2CCHC(O)OR(I), and 0 to 50% by weight based on the total amount of the reactive monomers M of at least one monomer M2, which is different from monomer M1, wherein the amounts of the monomers M1 and M2 are each based on the total amount of all reactive monomers M; a2) 0 to 30% by weight based on the total amount of the resulting aqueous polymer dispersion of at least one hydrophobic organic solvent; a3) 10 to 30% by weight based on the total amount of reactive monomers M of at least one protective colloid; a4) 0 to 24.5% by weight based on the total amount of the resulting aqueous polymer dispersion of at least one miscible solvent; a5) 0 to 5% by weight based on the total amount of the resulting aqueous polymer dispersion of at least one surfactant; and b) ultrasonic processing or homogenization of the aqueous monomer dispersion of step a); c) addition of at least one polymerization initiator.

12. The method according to claim 11, wherein the mixture obtained in step a) is treated with ultrasound for at least 10 minutes.

13. The method according to claim 11, wherein after step b) the aqueous monomer dispersion is obtained in form of a miniemulsion.

14. A method for depressing the pour point of crude oil, petroleum, or petroleum products by adding an aqueous dispersion according to claim 1 to the crude oil, petroleum, or petroleum products.

Description

EXAMPLES

(1) Used Starting Materials

(2) TABLE-US-00001 Shellsol high boiling aliphatic hydrocarbon mixture supplied by D70 Shell Chemicals, mostly C11-C14 aliphatic hydrocarbons (approx. 60% by weight paraffins, approx. 40% by weight cycloparaffins, aromatic hydrocarbons <100 ppm), initial boiling point 198 C. (ASDTM D86), flash point 74 C. (ASTM D93) Solvesso high boiling aromatic hydrocarbon mixture supplied by 150 ND ExxonMobil Chemical Company, aromatic hydrocarbon >99 vol %, initial boiling point 184 C. (ASTM D86), flash point 64 C. (ASTM D93) Behenyl isomer mixture of 40-55% by weight of C.sub.18-alkyl chain, acrylate <15% by weight of C.sub.20-alkyl chain and 35-45-% by weight of C.sub.22-alkyl chain, Behenyl acrylate BEA 1822F of BASF SE Protective modified styrene-acrylate polymer (M.sub.w ~8500 g/mol, acid Colloid number: 216, T.sub.g = 91 C.), neutralized with NH.sub.3, ~24 or ~41% by weight in water, Joncryl 678 of BASF SE Non-ionic C.sub.16C.sub.18 saturated fatty alcohol ethoxylate surfactant (C.sub.16C.sub.18O(CH.sub.2CH.sub.2O).sub.18H, Lutensol AT18 of BASF SE
Equipment

(3) Ultrasonic processor UP400s (Dr. Hilscher GmbH), sonotrode H14.

(4) Homogenizer APV 1000 (Kindler Maschinen AG): max. pressure: 1000 bar, capacity 22 L/h, charge volume 150 mL, volume in valve 13 ml

(5) Preparation of Miniemulsions

(6) The miniemulsion can be prepared by ultra-sonic processing or with a homogenizer. a) The macroemulsion is treated by ultra sound for 10 minutes with an amplitude of 100%. During the treatment the emulsion is cooled with a water bath. b) The second way to generate a miniemulsion is with a homogenizer. The macroemulsion is passed thru the apparatus at an applied pressure of 600 bar for 1 to 4 cycles.

Example 1

(7) A 2-L vessel equipped with stirrer and reflux was charged with a monomer containing dispersion under nitrogen atmosphere. The dispersion was prepared by mixing of a solution of 230.0 g behenyl acrylate in 135.0 g high boiling aromatic hydrocarbon mixture (Solvesso 150 ND) with a solution of 236.6 g protective colloid (24.3% in water, neutralized with NH.sub.3) and 57.5 g saturated C.sub.16C.sub.18 fatty alcohol ethoxylate (20% by weight in water, (C.sub.16C.sub.18O(CH.sub.2CH.sub.2O).sub.18H) in a water-glycol mixture (57.5 g demineralized water and 78.4 g of 1,2 propylene glycol). The dispersion was treated with ultrasonotrode for 10 minutes (100%). The reaction mixture was heated to 60 C. and 46.0 tert-butyl hydroperoxide solution (10% by weight in water) were added. Then 35.0 g of a 10% by weight-solution of sodium hydroxymethane sulfonate (aqueous) are fed over 1 h 30 min. The obtained polymer dispersion was cooled to room temperature.

Example 2

(8) A dispersion was manufactured according to example 1, however 135 g Shellsol D70 was used instead of Solvesso 150 ND. Furthermore, no 1,2-propylene glycol was added to the aqueous phase.

Example 3

(9) A dispersion was manufactured according to example 1, however 135 g heptane was used instead of Solvesso 150 ND.

Example 4

(10) A dispersion was manufactured according to example 1, however 230.0 g stearyl acrylate was used instead of behenyl acrylate.

Example 5

(11) A dispersion was manufactured according to example 1, however 230.0 g of a mixture of 95% by weight of behenyl acrylate and 5% by weight of n-butyl acrylate was used.

Example 6

(12) A dispersion was manufactured according to example 1, however 230.0 g of a mixture of 95% by weight of behenyl acrylate and 5% by weight of 2-ethyl hexyl acrylate was used.

Example 7

(13) A 2-L vessel equipped with stirrer and reflux was charged with a monomer containing dispersion under nitrogen atmosphere. The dispersion was prepared by mixing of a solution of 270.0 g melted behenyl with a solution 165.9 g protective colloid (40.7% in water, neutralized with NH.sub.3) in a water-glycol mixture (215.7 g demineralized water and 128.6 g of 1,2 propylene glycol) at 50 C. The dispersion was treated with ultrasonotrode for 10 minutes (100%). The reaction mixture was heated to 80 C. and 77.1 g sodium peroxosulfate are fed over 2 h 30 min. The obtained polymer dispersion was cooled to room temperature.

(14) Tests:

(15) Determination of the Pour Point (PP)

(16) The determination of the pour point was conducted according to ASTM D5853 Test Method for Pour Point of Crude Oils with a Pour Point tester PPT 45150 of PSL Systemtechnik, Germany. The pour point is the minimum temperature at which a sample of tested oil is still just free flowing. For the tests, a crude oil from the Landau oilfield in south-west Germany (Wintershall Holding GmbH) having an API gravity of 37 and a pour point of 24 C. was used. To determine the lowering of the pour point, the polymer dispersions to be tested were used in the oil in a concentration of 300 ppm of polymer based on the crude oil. The values are compiled in table 1. Double or triple determinations were conducted on some samples. In these cases, all measurements are reported in table 1.

(17) TABLE-US-00002 TABLE 1 Polymer dispersion used active particle content size d.sub.50 viscosity M.sub.N Mw PP ( C.) [wt-%] [nm] [mPas] [g/mol] [g/mol] (300 ppm) Comments V1 21; 24 Oil without additive 1 34.7 202 618 6810 42200 12; 15 Behenylacrylate in Solvesso 2 29.7 238 87 7280 109000 18; 18 Behenylacrylate in Shellsol 3 35.4 230 564 7170 273000 18; 18 Behenylacrylate in Heptane 4 33.4 216 652 4610 36300 12; 15 Stearyl acrylate in Solvesso 5 35.1 189 576 8310 55800 9; 12 95% behenyl acrylate, 5% butyl acrylate in Solvesso 6 36.9 169 546 8690 56300 9; 9 95% behenyl acrylate, 5% 2-ethyl hexyl acrylate in Solvesso 7 31.5 284 107 4150 102000 18; 18 behenyl acrylate without hydrophobic solvent and without surfactant
Analytical Methods
1) The solid content was analyzed with a halogen moisture analyzer, type HR73 (Mettler Toledo)
2) The molecular weight M.sub.w was analyzed by size exclusion chromatography (SEC) according to DIN 55672-1:1995-02 with THF as eluent and internal polymer standards. The method and the mode of action are known to the skilled person. Advantageously, the measurement is carried out in THF containing 0.1 wt-% trifluoroacetic acid and the method is at a flow rate of 1 ml/L and a column temperature of 35 C. The polymer emulsions are diluted to a concentration of 2 mg/mL and are filtered over 0.2 m filter (Sartorius Minisart SRP 25) to remove insoluble gel content. A sample of 100 l is injected. A column system is used consisting of three columns with an inner diameter of 7.5 mm (5 cm pre columnPlgel 10 Guard pre column) followed by two 30 cm separation columns (each Plgel 10 Mixed B). A differential refractometer Agilent 1100, UV-Photometer Agilent 110 VWD, PSS SLD7000-BI-MwA (UV/254 nm/Agilent) is used. The calibration is known to the expert and polystyrene standards are used (Polymer Laboratories with M.sub.w=580 to M.sub.w=7500000, and hexylbenzol (M=162).
3) Particle size distribution was measured with hydrodynamic chromatography (HDC) with a particle size distribution analyzer of the type PL-PSDA from Polymer Laboratories. Conditions: packed column (Cartridge PL0850-1020 (until 1200 nm), filled with polystyrene beads), flow rate 2 ml/min, pressure 3 MPa (30 bar), wavelength: 254 nm. The sample is filtered and diluted (absorption of 0.3 AU/volume unit).

(18) The eluent comprises the following surfactants and salts in demineralized water: 0.24 g/l sodium dihydrogen phosphat 0.5 g/l sodium dodecyl sulfate 2 g/l polyoxyethylen (23) laurylether (Brij35) 9.2 g/l sodium azide,
and has an pH value of about 5.5 to 6.

(19) In the column the sample was separated into its components by hydrodynamic diameter and eluted according to the size exclusion principle. The elution time was calibrated according to PS-Eichlatices and checked daily. The concentration of the components was measured by a UV detector in the range from 20 to 1200 nm. The detection was carried out at a wavelength of 254 nm.

(20) 4) Viscosity measurement was carried out via RVT-type Brookfield viscometer with a RV-3 spindle at 100 rpm.